Safety



I (No Mo'deL) H. G. SPALDING.

SAFETY DEVICE EOE ELEGTEIG CIRCUITS.

No. 327,500. Patented. Sept. 29, 1885.

UNITED STATE-s HENRY o. SPALDING, on nose-o sAFETYnEvioE FOR E5..-

ssncznrcn'rion forming part of Letters Application filed April 17, 1882.

lb all whom it may concern Be it known that I, HENRY G, SPALDING, of the city ofBoston, county oi'SuiYolk, and State of Massachusetts, have invented certain new and useful l'rnprovemenis'in Safety Devices for Electric Circuits, of which the following is a specification, reference being bad to the drawing accompanying and forming a part or" the same.

The object ofniy present invention is to pro tect in a more perfect manner than has here tofore been done electrical circuits the integrity of which is liable to be impaired or destroyed by excessive electrical changes. Among such circuits are those containing telephones, relays, or other delicate electrical 1G struinents, or those which are partially subterranean or subaqueous, and in which the insulation of the buried portions of the line is often injured or entirely destroyed by the passage of abnormal electrical currents.

Though applicable generally to electric cir cuits, the'device forming the subject of the invention is designed particularly for the pro tcction of subterranean or suhaqueous lines, and-I will therefore describe it as applied to this purpose.

In the-drawing annexed l have illustrated a device embodying my invention. Said device is composed mainly of alightningarrestor with separa'ted corrugated plates, at fusible safety-conductor, and an electro magnetic out-out, combined and arranged in certain relation, as will be more fully hereinafter explained.

The several parts of the apparatus are socured to a frame-work or support of suitable construction, designated by the letter A. To one part of this support is fixed a lightninga-rrester, B,of ordinary construction, having corrugated plates, one of which, as on, forms part of the circuit to be protected, while the other, b, is in good electrical connection with the ground by a wire, 0.

D is a wire or strip of metal having ahigher relative resistance than the conductors of the circuit with which it is connected. It constitutes a fusible safety device similar to those generally employed. E is an el'cctro-magnet, the coils of which are included in the circuit with the' devices described above. It is sup- Renown} February 21, 1884.

I l l l i invariably ported in a frame, poles down and in position to enertan' attraction upon an armature, c. This armature is carried by the short arm of pivoted lever, ll'the long arm of which is weighted and held up by a spring, 33, connected to the fusible wire l).

The long arm of the lever F is rounded oil to operate on a cum on the end of pivoted arm, G, which it forces forward against the force of gravity, or of a light spring, when, by the attraction of the magnet E or release of spring S, the long arm lowers.

in the path of movement of the post G is a pivoted or contact-arm, H, connected to a metallic standard electrical connection with the upper line platcol the lightning'hrraster B. "on the opposite side is a post, iii, connected to earth. The post G, arm H, and post K are to be normally in such close proxiniity that a slight movement only of the first will effect contact between the arm andihe post K.

on a standard, L,

is a device for interrupting the circuit.

That shown consists of two pivoted arms, fg, the former limited in its downward movement by an insulatingstop, the latterprovided with a retractile spring. The arms are connected to the line-conductors, as shown, so that when set or in contact the circuit will be completed through them. An extension, N, from the lever F, carrying an insulating-stop, raises the arm f and interrupts theoircuit when the lever F is tilted.

It will be observed that this apparatus is to be included in the circuit to be protected by connecting one end of the severed circuit to the line-plate of the lightning-arrester B,- the other to the arm 9, or a bindingpost in contact therewith. Currents will therefore pass through the wires 0 c, the safety-wire D, and coils of magnet E. The attractive force of this magnet, orthe tension of spring S, should beso adjusted that the armature will not be moved by currents of ordinary strength. Under these conditions the operation of the apparatus will be as follows: Should a charge of static electricity enter the line, it will generally leap across the space intervening between the corrugated. plates of the lightning-arrester B. In practice, however, it is found that this is not the case, and as a further precaution ICO I. add the wire' D, which being of relatively high resistance, is the first part of the line to (use on the passage of an abnormal charge. To prevent the current from bridging the space between the devices which hold the wire after it has been fused, I connect to it one end of the retractile spring S, so that simultaneously with the fusion of wire D a circuit is formed to ground by lever F, which brings arm post K. I

To prevent the injurious consequences to an underground line, or one containing delicate instruments, from the passage of strong currents-such as might be caused by the accidental contact of the line with an-electriclight circuitl employ the magnet E. The passage of-sueh a current would actuate the magnetbefore destroying the safety-wire D, so that the lever being tilted the circuitis disrupted by the separation of the contact-arms f and g. Ry thisineans a line may be protected' against all possible dangers from excessive charges.

I do not limit myself to the specific details of mechanism which I have described for the accomplishment of this result, as these may be considerably varied. I do, however, consider it essential to the successful operation of the apparatus that its several parts be combined and arranged relatively to one another in substantially the manner specified.

What I claim as my invention is 1. In an apparatus for the protection of the lowering of the long arm of H in contact with electric circuits, the combination of the light- 5 ning-arrester composed of the separated corrugated plates, one of which is in permanent connection with theearth with the fusible wire and devices, as described, connected therewith and adapted to operate, on the fusion of 0 the wire, to establish an earth-connection, by means of which the current may be diverted from the line in the manner set forth.

2. The combination, with a main electric circuit, of a fusible safety-wire included in 5 said circuit, a normally-open branch circuit to earth, and a mechanical circuit-closer connected with the fusible wire by a distensible spring, and constructed and arranged to on erate on the fusion ofthe safety-wire, and thereby close the said branch circuit, as and for the purpose set forth.

3. The combination, with a main electric circuit, of an electro-magnet, a pivoted armature-lever and circuit-breaker, a normallyopenbranch circuit to earth, and a circuitcloser connected therewith, a fus ble safety- 'wire included in the main circuit, and a spring sustaining the pivoted armature-lever con nected therewith',these parts being constructed and arranged for operation, substantially in the manner set forth. In testimony whereof I have hereunto set my hand this 14th day of April, 1882.

H. O. SPALDING.

Witnesses:

CHAS. E. BAGLEY, Burns Corrnv. 

